thats why those model t's come with a lovely thing called a hum balance. To use it, you need a plastic screwdriver. Once you get that, take off the back panel thinger. Then on the inside, there should be a tiny little hole in between the powertubes nearest you called "hum balance", take note of it. Plug in a patch cable, and let it hang, but dont let the tip touch anything or you'll get an earful. Next turn on your model t, and turn EVERYTHING to 10. It will be noisey. Now stick your plastic screwdriver into the hum balance, and turn until the noise is reduced. If this doesnt work, its your tubes.